The use of rotatable valves is well known as is the use of check valves which include a mechanism for stopping the flow of fluid in one direction while permitting it in another direction. Check valves normally are unidirectional, that is, permit flow in one direction and block flow in the other direction, and there is no means of reversing this condition without completely removing the valve from its installation and reversing the orientation of the valve.
Others have provided check valves in which the check action of the valve can be reversed. In one condition, the valve permits flow in a first direction while prohibiting flow in the second direction; The internal orientation of the valve can be reversed so that the valve then permits flow in the second direction while preventing flow in the first direction. For reference to prior art relating to such reversible check valves, reference may be had to the following U.S. Pat. Nos. 3,851,665; 3,474,818; 3,363,650; 1,175,328; 2,151,098; and 3,344,808.
These prior art devices disclose useful basic concepts, but each of the valves shown in these designs have inherent problems. One problem which frequently exists with check valves is that after a period of usage, the pivotal mechanism within the valve which functions to permit flow in one direction while blocking it in the other, can become worn, and wear is usually accelerated by the erosion of fluid flow through the valve. In addition, many check valves have elastomeric seats to obtain complete closure. These elastomeric seats can deteriorate. For these and other reasons it is sometimes necessary that the checking mechanism be removed for repair or replacement. In check valves of the known type, all fluid pressure to the valve must be shut-off, otherwise when the valve is open for repair, leakage of fluid is permitted.
The present disclosure is directed towards a valve which provides a check action in either direction, selectable by the user of the valve, and which provides complete fluid flow shut-off when desired. The valve, thus, will replace a number of separate valves and fittings. In addition to these features, it provides a valve in which the checking mechanism may be removed for repair or replacement while the valve is under fluid pressure and without permitting leakage of fluid.
The present disclosure is also directed towards a mechanism for use in valves that will automatically increase the sealing force of the rotating member when the valve is in the fully closed position and reduce the sealing force when the rotating member is in any other position, thereby providing a valve with its greatest sealing force when required and reduced wear. Additionally, the sealing force may be adjusted while the valve is under fluid pressure.